'. ~ . ,. I • ~ I • • .. j. to • Of Ii , II .. .. .. .. • : II .. : " - - - - W 12.8 W 2.8 112.5 W Ell I~~~ 1 W - ItiJiij wW 2.2 W W W1 2.2 I:.l I:.l IKlI!iiii!!i!5 I:.:W I:.: W'- 11&. ..4.0 w : ~ : w .......... " ......." "I"l~ I I~" 1.8 ."'" 1.25 111111.4 ""'1.6. ""'1.25 111111.4 1111,1.6. MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAUOFSTANDAROS-1963-A NATIONAL BUREAU OF STANoAROS-1963-A . .I.) :.,.,. "." ' ......., Technical Bulletin No. 504 January 1936 UNITED STATES DEPARTlv1ENT OF AGRICULTURE WASHINGTON, D. C. ORIDS INSIDIOSUS (SAY), AN IMPORTANT NATURAL ENEMY OF THE CORN EAR WORM By G. \V. BAltB1ilR AssOCIate entom,%gist, DivillioJl. of Oereal uncI Pora[le insect TwvesUgations, Burc!I'lI, of Entomo7.0gll alta Plant Quarantine CONTENTS l'nge Puge Introduction ________________________________ ._ 1 Food habits of adults__________________________ 12 Economic importnllcc _________________ •_____ ._ 2 I,ength of life of adults______________________ 13 Heview orliteraturll ____ •___________ ••__ • _'.__ 2 Proportion of sexes.___________________________ 13 OYiposltion______ ___________________________ 14 Oriusworm inBidiDBUS_________ in • ___reiation • ______________ to the com ._____ ear 2 'rho egg __________________________________ • 14 Places chosen for egg laylng____ -__________ 14 Oriusand in8idiDslI.sto miles___________ in relation- _______________ to otPer insccL~ ._ 3 Seasonal ,history _____ ._________________________ 4 Relationcapacity.- of food______________________ ofadults to their egg-laying .._______ 15 Before corn becomes available_____________ 4 Relation of Elza oC eggs to the egg-laying On the corn plant. ________________________ 4 habits_________________________ •• ___..___ 17 Abundanceon corn plants in their severnl stages Incompleted o\,iposition__________________ 18 of growth___________________________________ 0 The nymphs_~ ~ _______________________________ 18 Occurrence on tho several parts of the corn Number of generations on corn________________ 18 Tho importance of Orius i1!~idioSU8 in the nnt­ ~1:ti;e-ati;iiCtivc;lcss-ordffie;e~tv;;rici:jeS-or 8 Sllllilllaryural control__ .__________________________________ of the corn elll' worm____________ 2119 ~.rtloDsiiipoitbe-S(;iiso-niiiiiistOryiiii(iiibuiitr- 10 Literature cited_______ ________________________ 22 ance of Orill8 i'7l8idiolfU8 on corn plnnts to the C"':)COrn elll' worm_______________________________ 10 C\l 0::: ~ INTRODUCTION :iE In the course of a, st.udy at Richmond 1111<1 Charlot.tesville, Va., from 1924 to 1927, on field oviposition by the corn ear worm (Helw­ tlli8 obsoleta Fab.) and the fate of the eggs deposited on corn, it was found that the most important natural destroyer of ear worm eggs, especially those deposited on corn silks, was the smallantho­ corid bug, OJ'ius insidiosU8 (Say), formerly known as TriplLleps in­ SidWSU8. The writer has previously observed its abundance on corn and its import/ant relationship to the European corn borer in Mas­ saChusetts (93) ,1 and the literature showed that it. was widely dis­ tributed, not only on corn but on many other plants, where it fed on numerous small insects many of which were injurious to crops. All of this information was fragmentary, and it appeared that little 1 Itallcnumbers in parenthes('s refer to Ut!!rntllre Clt'ld, p. 22. 20240°-36-1 1 2 TECHNICAL BULLETIN 504, U. S. DEPT. OF AGlUCUHI:UTIE was knmv'Il about the biology or economic importance of this ubeful predator. During the years 1928 and 1929, in the vicinity of Rich­ mond, Va.) the ,Yriter le'arnedmuch 1110re about this species, especially as found 011 the corn plant and as related to the corn ear worm, and the information gained ill this study is sUIllmarized in the present bulletin, ECONOMIC IMPORTANCE 01'ius in.<tidiosus apparently occurs over most of the Uniteu Staies and in southern Canada. Records ill literature show its occurrence jn 31 States as well as in 2 Canauian Provinces. It occupies among the Hemiptera a position similar to that occupied hy T)'ic7lO(J7'a7n1n((' 1111inut-wn Riley among the parasit.ic Hymenoptera, for frequently these 1,yO smtiH species, taken together, form the most hnportant ~atura,l control of an injurious insect, especia1ly among those attack­ mg the corn plant, the one destroying the eggs alolJ{~, and the. other feeding on Loth eggs and newly hatched larvae. lvI. p, Jones, in a.', 'lnpublisheu llllU11l;;cript, reports tbat (Tl'iph­ leps) 01"ius insidio8U8 was fonnd feeding on probably 4 percent of the pupae of the Mexican bean bean beetle (Epihu:ltna C01'l"upta Muls.) late in June. 1924. The insects attucked by O. -iruJidio8U8, aC('ording t() the "writer's observaHon in various localities, were among the most important enemies of the corn plant in these several areas and included 1)01 only the corn ear worm but the European corn borer (Pyrau8trt 11flf,bil.aU,'{ Hbn.), in Mas:-,achusett.s in 1923 and 1924, the fall nrmr worm (Lapltygma. fr16(Jiperdct S. and A.). in Georgia in 1930,and the larger corn st.alk borer (Diatraea c.l'wnbidoides Grote), in Virginia in 19~8 and 1929, REVIEW OF LITERATURE Notes from published writings show that O. in8idio8U,~ not only occurs wielely over the country' but is found on a "'ide variety of vegetation, including trees, shrubs. field crops, Yegetables, and many wild plants. On many of these it. is found principally on the blos­ soms, but it also searches for food oYer the en6re plant. Wh,'11 corn is available. it lays its eggs pr.incipa.lly in the strlll1ds of fl'esh silk, .vhere also the young nymphs Legin feeding. ORIUS INSIDIOSUS IN RELATION TO THE CORN EAR WORM Forbe.c; records O. 111Sidio8US as an ('nemy of corn (':11' worm egg,; and ()3) notes its abundance on ('orn. Garman and J ('wett (16) reared O. insidio8US from the egg, and figured the egg;; fot· the first time; they reckoned its life cyde JroIll l'gg to ndult as 15 days, 3.25 hours. They state (16, 'fl. 587): "It appears to feed to Home. extent on plant jui<.:es, but is fond of lhl' juices of various insects, such as species of 'thrips,' and is very usef'ul because of its destrllction of the eggs of the corn wor111." Many (.39, p. 39) noted that this insect was Leneficial in destroying bollworm eggs. Quaintancp and Brues (36, p. 107), il~ an elaborate report on the bollwol'lll say: The nyrupllS and ntlults of: ~l'rillhT('pg i1!8idiosu..~ Sa)" .. * * hare been r<.'peatedly obScrvell feeding on bollworlll eggs aml on ..ery HlIlnll llll'\'Ue. 'l'his IIttle heterclJlterQll is especially almn(lallt ill fresh com I"ilk. Hnll is !lflplI f;f'ell frequenting cotton vlants also. Although ill a nUlIIber of Jnstances noticed in ORIUS INSIDIOSUS, ENEl\fY OF CORN EAR WORM 3 the laboratory they seem loath to attack liYing larvae, they are sometimes .to be seen In the field with newly hatched larvae impaled on their slender beaks. Their prinCipal vnluu lies, however, in the large number of eggs which they destroy. A special count was made at Sulphur Springs, Tex., on AUb'1lst IG. 1904, to lletermine the probable proportion of eggs destroyed hy this agency. The eggs on 10 different silking ears were examined, and, on an uyerage, 55 percent of the eggs were found to be shriyeled. It is probable that most of •these shriveled eggs had been punctured and their contents sucked out by the Triphleps, which were numerous 011 the silks at that time. r.rilis is no doubt an exceptional case but it serves to show of what great value the Tripbleps lllay be under favorable conditions. Webster (43) lloted as early as 1885 that O. insidio8US may fre­ quently be found in all stages literally swarming among the corn silks with no other visible food supply. 'Winburn and Painter (5(}) state, regarding the corn ear WOI'I11: "Among the prec1atol's, 01'iu8 insidio8U.<j is l)l'obably t11e most bC'neficial." ORIUS INSIDIOSUS IN RELATION TO OTHER INSECTS AND TO l\UTES Besides the eggs and young larvae of Lepidoptera, tht' insects recorded as prey of 01·i.W~ in.sirlio8u8 include thrips, aphids, white flies, leaf hoppers, the young of lace bugs, the chinch bug, midges. red spiders, and mites. One writer (128) rt'corc1s it as even attacking man. Another (gO) thought that it tl'ansmittt'cl corn-ear rot (Diplo­ elia, sp., Fusai'I1.l7i1. sp.). Still another (89) rl'ferrecl to the feeding­ and l'gg-la.ying injury to chrysanthemums attributed to O. in8ieli'()8u..~. A list of insects prl'}'l'd upon by O. i1udclio81.t8 anel references to recor<1~ of sueh aHack in literature follow: 1'hYRHllOjltrl'U (n, p. ·~.'I4; 42) : Thrip.¥ tabaci Lind. (4. in. RIIII/rips nico/ialllle Hinds (=F'rll1/klinid!a. flll'('a I-Iillll:;) (18). EllthriJl'~ IlYri, Daniel (='faclllolilriI/8 il1ron8('f]I/('/I.~ l'z('1) (15). (EII/ltri,M) Sc/rtuthrip8 citri Muult. (UJ). Fnmk7inidla. Iritiei l!'itrb (1111. ProsopOO,.rip8 coglla tt/.s Hood (.!,~ L Hcliolhrip8 fa.sciatns PeJ'g. (.l01. H(lmopt:rrn : (Ma{:1·oNiphu.m) !lUnoia. Ilisi Knit. (6; If. /I. t51). Phll110;crra 1'ilifoliar Fiteh (12, 11. IW; q; 2.'J), .1fllZU8 iJra[l{fii GilH'tte (21). Pho1'Odon hUIII1/li Schrank (.'J.'I). ((,IIU ito!)h()rll..~) P(·rip1t1l111l..~ /lrgllll/liniN Tho>'. (.~!ll. (Al('lIrO(le.~) Trialcuro(l(',~ 'l'IlJlorariOrlllll ·W(>~tw. (16). EIII ]10(lS('1I mali Le Darou (= B1/I.poa.~('a· fa IHI(' I-Ian.) (1 .. ·Ii .. .'JR, 11.400). Hrmi)Jtel'fl: OorlJ/l/·llclt(l. ciliala SIQ' (31,.'Jt). Gm'gaphia, .~o!olli Heid. (9). B/i.~MIS 1('1(('0]111'1'1/8 Sny (10; 12, p. Ra; 11; 2.'3; .18; H; I,;;j ·Hi).